9.12.2.2 Register Names

You can use predefined symbols of the form ‘rnh
’ and ‘rnl
’ to refer to the H8/300 registers as sixteen 8-bit general-purpose registers. n
is a digit from ‘0
’ to ‘7
’); for instance, both ‘r0h
’ and ‘r7l
’ are valid register names.

You can also use the eight predefined symbols ‘rn
’ to refer to the H8/300 registers as 16-bit registers (you must use this form for addressing).

On the H8/300H, you can also use the eight predefined symbols ‘ern
’ (‘er0
’ ...
‘er7
’) to refer to the 32-bit general purpose registers.

The two control registers are called pc
(program counter; a 16-bit register, except on the H8/300H where it is 24 bits) and ccr
(condition code register; an 8-bit register). r7
is used as the stack pointer, and can also be called sp
.